The present invention relates to a display driver and an electronic instrument.
In recent years, a high-speed serial transfer interface such as a low voltage differential signaling (LVDS) interface has attracted attention as an interface aiming at reducing EMI noise or the like. In such a high-speed serial transfer, data is transferred by causing a transmitter circuit to transmit serialized data using differential signals and causing a receiver circuit to differentially amplify the differential signals (JP-A-2001-222249).
An ordinary portable telephone includes a first instrument section provided with buttons for inputting a telephone number or a character, a second instrument section provided with a main liquid crystal display (LCD), a sub LCD, or a camera, and a connection section (e.g. hinge) which connects the first and second instrument sections. The number of interconnects passing through the connection section can be reduced by transferring data between a first substrate of the first instrument section and a second substrate of the second instrument section by serial transfer using differential signals.
A sub LCD is generally provided in the second instrument section of a portable telephone in addition to a main LCD. It is desirable that the sub LCD be controlled by a display driver which drives the main LCD in order to reduce the number of parts of the portable telephone.
A host device (e.g. MPU, baseband engine, or display controller) provided in the first instrument section transfers data at high speed through a high-speed serial bus. The operation speed of a sub display driver which drives the sub LCD is generally lower than that of the display driver for the main LCD. Therefore, if the data transferred from the host device through the high-speed serial bus is directly output to the sub display driver, there may be a case where the sub display driver cannot receive the data.